DOOM: Legions of Hell

DOOM: Legions of Hell is a modification for Wolfenstein 3D similar to Wolfendoom by AReyeP, only trying to more closely replicate Doom. It was first released as a vanilla mod for with the latest version being 1.02.

It was later ported to the Wolf4SDL source port for better performance and compatibility; particularly in terms of rendering the game's floors, ceilings and backdrops. It was created by insurrectionman and first released on June 26, 2007, with the SDL version out on December 25, 2012.

A follow up was also released in 2010 called DOOM: Legions Revisited.

Trivia
I have tested it on an old 386 computer and it worked, except for a few areas where it was out of memory. And in-game has super-slow frame rate. It took 10 minutes to load the shade tables. I hope you aren't running a computer like that, otherwise you might as well forget playing this game...
 * A similar mod exists called Klooni, which requires the original Doom II or Final Doom WAD files to run.
 * The version for DOS that is currently available (1.02) suffers from being very limited in memory usage and may crash while playing. According to the developer:

"PM_GetPage: Invalid request" happens often, but that cannot be helped.

"MM_GetPtr: Out of Memory" is going to happen a lot on low-end computers.

The memory problems will be fixed in the DOS\4GW version of the game. Which will come out next. I don't know when. The DOS\4GW version was not released.